This invention relates to a feed paper apparatus for feeding paper and an image forming apparatus such as a copying machine having the feed paper apparatus.
In above the copying machine, various types of feed paper apparatuses are provided for paper feeding.
As one of large-capacity feed paper apparatuses, a large capacity feeder of tandem type (which is hereinafter referred to as a tandem type LCF) is provided.
It has two boxes (first and second boxes) for storing paper in the feed paper apparatus, and if paper does not exist in one of the boxes (first box), paper is moved from the other box (second box) to one of the boxes (first box) so that the paper feeding operation can be continued.
In this case, a series of processes from occurrence of no paper to the restart of paper feeding after the movement of paper from the other box (second box) to one of the boxes (first box) is defined as a transfer process.
As a result, it becomes possible to simultaneously supplement a large amount of paper and reduce the chances for interrupting the printing operation due to no paper or supplementing paper by the user.
Since only one box is provided in the unit in the conventional feed paper apparatus, there occurs no problem if paper is set according to the size thereof.
However, in the tandem type LCF, two boxes are provided in the unit. The two boxes are separated by a driving guide (which is hereinafter referred to as an end guide) and the user correctly sets paper into the two boxes according to the guide. If the user does not correctly set paper, a sensor attached to the end guide detects abnormality and warns the user that paper is not correctly set.
However, even if paper is correctly set, the user must withdraw the unit again by the warning and set paper if paper lies over the guide even a bit and it is detected as abnormality. As a result, it takes a lot of time and labor for the user.
If detection of abnormality by the guide is neglected and the tray-up or transfer process is effected in order to avoid this, damage or failure of the feed paper apparatus may occur and it is not an apparatus which is safe and highly reliable.